Time resolved measurements of hydrogen ion energy distributions in a pulsed 2.45 GHz microwave plasma

Abstract

A plasma diagnostic study of the Ion Energy Distribution Functions (IEDFs) of H þ , H þ 2 , and H þ 3 ions in a 2.45 GHz hydrogen plasma reactor called TIPS is presented. The measurements are conducted by using a Plasma Ion Mass Spectrometer with an energy sector and a quadrupole detector from HIDEN Analytical Limited in order to select an ion species and to measure its energy distribution. The reactor is operated in the pulsed mode at 100 Hz with a duty cycle of 10% (1 ms pulse width). The IEDFs of H þ , H þ 2 , and H þ 3 are obtained each 5 ls with 1 ls time resolution throughout the entire pulse. The temporal evolution of the plasma potential and ion temperature of H þ is derived from the data. It is shown that the plasma potential is within the range of 15-20 V, while the ion temperature reaches values of 0.25-1 eV during the pulse and exhibits a fast transient peak when the microwave radiation is switched off. Finally, the ion temperatures are used to predict the transverse thermal emittance of a proton beam extracted from 2.45 GHz microwave discharges.

Bimodal ion energy distribution functions in a hydrogen magnetized plasma

“…These results strongly contrast with those of a previous study recently published by the authors about the IEDF temporal evolution for the column mode, where no split in the IEDFs was observed [10,16]. For that case, the calculations of the ion temperatures were made by transforming the IEDFs into ion velocity distribution functions (IVDFs).…”

“…The second setup was used to measure the temporal evolution of the IEDFs using a plasma ion mass spectrometer that uses a 45°energy sector analyzer in tandem with a quadrupole mass analyzer [16]. This configuration is able to select a particular ion (mass and charge) to measure the corresponding energy distribution.…”

Mass spectroscopic measurement of time-varying ion composition in a pulse-modulated Ar/C4F8/O2 dual-frequency capacitively coupled plasma

“…15,16) Considering that the HAR etching plasma is operated in the pulsed mode, the etching performance may be influenced by the time-dependent behavior of positive ion species. There have been several experimental or theoretical reports on time-resolved measurements of ions with single rare or halogen gas, [17][18][19][20] or simple fluorocarbon gas. 21,22) However, to the best of our knowledge, no study has been reported on pulse-modulated Ar/C 4 F 8 /O 2 DF-CCP, which is commonly used in the HAR etching of silicon dielectric films.…”